No, unfortunately it is not possible to link your Facebook Chess account to your Chess.com account. They are two separate entities.
Chess Application on Facebook
Will it be possible in the future?
Anything is possible. You just have to believe.
No, probably not...

That sucks. Stumbleupon has full integration between facebook and the outside account. You are shooting yourself in the foot with this half hearted design as facebook users will not move over to your full featured community with the paid for functions. A very poor model when you put so many obtacles in the way of buying but give your main functionality for free.
Is there any way I can link the chess.com chess application on facebook with my chess.com account here?